The ultimate enemy: weeds

Oct 06, 2011

Weeds are some of the toughest foes corn and soybean growers face. Unfortunately, weeds can win the battle, as seen with the herbicide resistance that is spreading across the Corn Belt. Here are some of the toughest field foes growers must tackle.

1. Waterhemp

"Twenty years ago, waterhemp wasn't even on the radar in Illinois," says Aaron Hager, weed specialist, University of Illinois. Today, waterhemp is a weed of major concern. Photo: Mike Krivit

2. Giant ragweed

Herbicide-resistant giant ragweed is showing up in the Midwest. This weed has adapted to cultivation practices as well, relegating it to true "foe" status. Photo: Mike Krivit

3. Marestail

Bayer CropScience's new Corvus preemergent and Capreno postemergent herbicides with three modes of action are formulated to control marestail, also known as horseweed. Photo: Mike Krivit

4. Pigweed

Glyphosate-resistant Palmer pigweed has quickly spread across the South and into the Midwest. One plant produces more than a half million seeds. Floods in Arkansas spread those seeds across 100,000 acres last spring, creating a nightmare weed mess for growers. Photo: Mike Krivit

5. Giant ragweed

Giant ragweed earned its name by reaching heights of 16 ft. when left untreated. Resistant giant ragweed has shown up in nine states. Photo: Mike Krivit

6. Lambsquarter

Lambsquarter is not officially on the glyphosate-resistant list, but is showing signs of high tolerance and inconsistent control in the Midwest and South. Photo: Mike Krivit

7. Velvetleaf

Although not on the glyphosate-resistant list, velvetleaf remains a big foe for growers in the Midwest. Its velvety leaves belie the plant's ability to thrive in corn and soybean fields. Photo: Mike Krivit